Motor-control system



April 15 1924. r 1,490,197

E. M. BOUTON MOTOR CONTROL SYSTEM Filed Aug. 17 1920 eg'uen cc ofOperation C'ut. fiet O O O INVENTOR WITNESSES:

' l ATTORNEY Patented Apr. 15, 1924.

, UNITED, STATES PATENT OFFICE.

sneer. x. BOUTON, or w nxmsnusc, rENNsYLvANm, ASSIGNOR 'ro wnsrmenousnsnncmca namincruame COMYANY, a coaroaarron or rnNNsYL- VANIA.

MOTOR-CONTROL SYSTEM.

Application flied August 17, 1920. Serial Io. 404,048.

Allegheny and State of Pennsylvania, have invented a new and useful Imrovement in Motor-Control Systems, of w ich the following is aspecification.

My invention relates to. motor-control systems and it has particularrelation to systems for operating motors which must repeatedly reversetheir direction of 0 ration, such, for example, as reversing p anermotors.

The principal object of my invention is to provide protective devices toprevent a planer from over-traveling when the motor fails to reverseitself because of its directkinal contactors failing to function propery.

The second object of my invention is to provide several dynamic-brakingcircuits for a motor in accordance with the different conditions towhich the motor is subjected. It will be apparent to those skilled inthe art that less resistance for the dynamicbraking circuit is requiredwhen the contactors for a motor open because of low voltage, forexample, than in an emergency, such as when the motor over-travelsthrough some failure in'the control system.

Heretofore, in some cases, motors have been provided with dynamicbraking cir-- cuits for each direction of travel thereof. These controlcircuits have not always-properly functioned, as sometimes a motorcontinued to operate in one direction beyond the point where it shouldhave reversed, and unless some protective means was attached to themotor or a machine driven thereby,

injury was liable to result to both.

Briefly speakin my invention consists in providing additional contactorsfor opening the armature circuit ofa motor, when the motor over-travels,and having other contactors co-operatin with them to complete adynamic-braking circuit for stop- I ping the motor.

A better understanding of my inventionmay be secured by referring to theaccompanying drawi,

Fig. 1 of whic is a schematic view of a motor-control system designed inaccord: anoe with -my invention;

troller 32 is so actuated b Fig. 2 is a diagrammatic view of a controlsystem shown in Fig. 1;

Fig. 3 is a uence chart showing the order in which t e contactors of thecontrol system shown in Figs; 1 and 2 close .for the various operationsof the motor.

Referring particularly to Figs. 1 and 2, a motor 21 having an armature22, a series field winding 23 and a shunt field-ma etwinding 24, iselectrically energized rom line conductors 25 and 26. The direction of oration of the motor 21 is controlled by t e customary directionaloontactors 1, 2, 3 and 4;. Auxiliary contactors 1A and 2A aremechanically interlocked with contactors 1 and 2, respectively, inaccordance with a familiar practice. V

Contactors 7 and 8, having auxiliary con-- tactors 7A and 8Arespectively secured thereto, are controlled by over-travel limitswitches 27 and 28, respectively. A contactor 11 is provided forshunting a starting resistor 29 which is in series with the motor 22. Anauxiliary contactor 11A is mechanically connected to the contactor 11and, when closed, provides a shunt circuit for the shunt field-magnetwindin 24: around the field resistor. A dynamic-fire];- ing resistor 31is j electrically connected to the contactors 1A, 2A, 7A and 8A.

A master controller 32 controls the direction of o eration of the motor21 by being electrically connected to the actuating coils of the sets ofdirectional contactors 1 and 3, and 2 and 4. The master controller 32has a'central ofi position and a cut' or forward position and a returnposition on opposite sides of the off position. The off position is alsothe dynamic-braking sition for the motor in both the cut an the returndirections.

The operation of the control system is begun by moving a contact segmentof the master controller 32 from the 0E position to either the left orthe right thereof, in

accordance with the position of the machine which is actuated by themotor. Theconthe planer or other machine not shown driven by the motor.21 that a r the planer has traveled a given distance, the controller 32is reversed. The controller 32 may, however, be manuallzpperated duringthe starting of the mac terminal 38, contact When the contact se ent 33is brou ht to the cut position of t e master contro ler 32, a circuit isestablished from line conductor 25 through conductor 35, actuating coil36 of the mechanically connected coutactors 2, 2A and 4, conductor 37,contact cut 33, contact terminal 39 and conductor 40 to line conductor26. The completion of this circuit energizes the actuating coil 36 andcauses the contactors 2 and 4 to close and contactor 2A to open.

A mam circuit now extends from the line conductor 25 through conductor43, series field-magnet winding 23, conductors 44 and 45 and contactor 2as far as contactor 7.

The contactor 7 is closed whenever a line switch (not shown)electrically connects the line conductors 25 and 26 to a source ofelectrical energy. The corresponding auxiliary circuit is establishedfrom the line con ductor 25 through conductors 48 and 49, actuating coil51, conductor 52, contact bridge 28 of the over-travel limit switch 28and conductor 54 to line conductor 26. lhe actuating coil 51, beingenergized, will effect the closing of the contactor 7 and the opening ofcontactor 7A.

The contactor 7 being closed, the main circuit from contactor 2 iscontinued through contactor 7 and conductor 55 to the armature 22 of themotor 21 and thence, through conductor 60, contactor 4, conductor 61 andresistor 29, to line conductor 26. The completion of this circuit causesthe armature 22 and the series field-magnet winding 23 to be energized,thereby starting the motor 21.

The shunt field-magnet winding 24 has already been energized by acircuit from line conductor 25 through conductors 48 and 62,field-magnet winding 24, conductors 63 and 64, contactor 11A andconductor 67 to line conductor 26. The motor 21 will continue to drivethe planer in the cut direction until the planer actuates the contactsegment 33 in a reverse direction by a mechanism which is not shown, butwhich is wellknown in the art. As soon as the circuit is broken throughthe contact terminals 38 and 39 by the contact segment 33 being movedtherefrom, the actuating coil 36 is de-energized, whereupon thecontactors 2 and 4 return to their normal open position and thecontactor 2A is closed.

A dynamic-braking circuit is established through the resistor 31 by theclosing of the contactor 2A, as the contactor 1A is normally closedduring the cut direction of rotation. This circuit is established fromthe contactor 2A through holding coil 69, conductor 70, dynamic-brakingresistor 31, conductor 71, holding coil 72, contactor 1A, conductor 75,contactor 8, which is normally closed when the line conductors 25 and 26are energized, conductor 76, armature 22,

conductor 55, contactor 7 and conductor 79 to contactor 2A. Thecompletion of this dynamic-braking circuit quickly stops the motor andplaner, and when the contact segment 33 has been moved by'the machine tothe return position, the motor reverses its operation, causing themachine to move in the return direction.

The auxiliary circuit which maintains the contact bridge 8 in its closedposition when the line conductors 25 and 26 are energized is establishedfrom line conductor 25 through conductors 48 and 49, and 80, actu atingcoil 81 of the contactor 8, conductor 82, contact bridge 27a of theover-travel limit switch 27 and conductors 83 and 54 to line conductor26.

When the contact segment 33 occupies the return position, an auxiliarycircuit is established from line conductor 25 through conductor 84,actuating coil 85 of the contactors 1, 1A and 3, conductor 86, contactfinger 87, of the master controller 21, contact segment 33, contactfinger 88 and conductors 89 and 40 to line conductor 26. The completionof this circuit energizes the actuating coil 85, thereby closing themechanically connected contactors 1 and 3 and openin contactor 1A. I

en the contactors 1 and 3 are closed, a main circuit is established fromthe line conductor 25 through conductor 43, series field-magnet winding23, conductors 44 and 90, contactor 1, conductor 75, contactor 8,conductor 76, armature 22, conductors 55 and 92, contactor 3, conductors94 and 95 and starting resistor 29 to line conductor 26. The completionof this circuit causes the motor 21 to operate in a reverse direction,for it is apparent that the series field-magnet winding 23 and the shuntfield-magnet winding 24 are energized in the same direction and only thecurrent through the armature has been reversed from that employed inoperating the motor in the out direction.

After the motor has driven the machine a predetermined distance in thereverse direction, the contact segment 33 is moved in a forwarddirection by the same device heretofore mentioned, which is actuated bythe planer or machine. The movement of the contact segment 33 breaks thecircuit through contact fingers 87 and 88, thereby de-energizing theactuating coil 85 of the contactors 1, 1A and 3, causing the contav tors1 and 3 to open and the contactor 1A to close. Since the contactor 2A isnormally closed during the return operation, the closing of thecontactor 1A establishes the same dynamic-braking circuit, as hasalready been described in connection with dynamic braking when the motoris operating in the cut I direction.

The contact segment 33 is thus again actuatod to the cut position of thecontroller 32 and-the motor 21 is again operated so as to in both theforward and the reverse operation by shunting the starting resistor 29,which is in series with the motor armature 22, and by weakening theenergization of the shunt field-magnet winding 24. Both of theseoperations are performed by energizing an actuating coil 96 of themechanically connected contactors 11 and 11A, thereby causing thecontactor 11 to close and the contactor 11A to open. The circuit forenergizing the actuating coil 96 extends from the armature 22 throu hconductors 76 and 97 to contact terminal 98 of the relay 99,contact'terminal 100, (the relay 99 being closed when the contactor 8 isclosed) conductor 101, contact terminal 102 of the relay 103, contactterminal 104 (the relay 103 being closed when the contactor 7 isclosed), conductor 105, actuating coil 96 and conductor 106 to thearmature 22.

It is apparent that this circuit is energized by the counter E. M. F.generated by the armature 22 and, after the motor has reached acertain'speed, the coil 96 becomes sufiiciently energized to close thecontactor 11, thereby establishing a shunt circuit from the conductor 95at the armature end of the starting resistor 29 through conductor 107,contactor 11 and conductor 67 to line conductor 26.

At the same time that the starting resistor 29 is shunted, the shuntfield-magnet winding 24 is weakened by the resistor 30 being placed inseries therewith upon the opening of the shunt circuit around theresistor 30 through contactor 11A. The shunt fieldmagnet winding 24 isthen energized from the line conductor 25 through conductors 48 and 62,shunt field-magnet winding 24, conductors 63 and 109, resistor 30 andconductors 110 and 67 to line conductor 26.

If, for any reason, the directional contactors 1, 2, 3 and 4 fail. tooperate properly, the planer will continue to travel in either a forwardor a reverse direction until it strikes an arm of one of the over-travellimit switches 27 or 28.

Assuming that, for some reason, the contactors 2 and 4 fail to open andthe ma chine continues to operate in a cut direction until the planerstrikes the arm 28b of the over-travel limit switch 28, the switch 28will be opened to break the circuit throu h the actuating coil 51 of thecontactor 7 When the actuating coil 51 is de-energized, contactor 7will-open,

thereby breaking the circuit through the the motor armature 22, andcontactor 7A will close, thus establishing a d amic-brakin circuit fromthe contactor .7 through hol ing coil 112, conductor 113, a portion ofthe dynamic braking resistor 31, conductor 71, holding coil 72,contactor 1A, conductor 7 5. contactor 8, conductor 76, armature 22 andconductors 55 and 114 to contactor 7A. The completion of thisdynamic-braking circuit through the larger portion of the resistor1 31W111 quickly stop the motor 21 and aner.

S1milar protective means is also provided for the motor, when operatingin a reverse direction, by the planer striking the arm 27b of theover-travel limit switch 27 should the planer travel too far. When thearm 27b. is struck, the contact bridge 27a breaks the circuit throughthe actuating coil 81- of the mechanically connected contactors 8 and8A, thereby openin contactor 8 and closing contactor SA. is establishesa circuit from the contactor 8A through holding coil 116, conductor 117,a portion of d namic-braking resistor 31, conductor 70, olding coil 69,contactor 2A, conductor 79, contactor 7 conductor 55, armature 22 andconductors 76 and 118 to contactor 8A. This dynamic-braking, eir cuitincludes a portion of the resistor substantially equal to that used inapplying dynamic braking when the over-travel limit switch 28 is openedby the machine overtraveling in the cut direction.

It may be noted that the contactors 8 and 8A are provided with an arm 85and that the contactors 7 and. 7A are provided with a similar arm 7 b.The actuating coil 96 is tie-energized when either of these arms is inits lower position, thereby causing the contactor 11 to open and thecontainer 11A to 'close. The p as of closing the contactor 11A is toshunt the field resistor 30, which is in series with the shuntfieldmagnet winding 24, and thus provide as strong a. field as ossible,when efiecting dynamic braking of the motor 21 during its o'vertravel.

A third system of dynamic bra b provided when the contactors 1, 2, 3, 4,8 and 11 open because of low line voltage. The contactors are then intheir res ectwe .positions, shown in Figs. 1 and .2. .Jne directionalcontactors 1, 2, 3 and 4 and the conductor 113, a relatively smallportion of. the dynamic resistor 31, conductor 117,-

holding coil 116, contactor 8A and conductors 118 and 76-to the-armature22.

By my invention I have provideda coni resistor when the contactors areopened because of low voltage.

While I have shown my invention in its preferred form, it is apparentthat modifications in the apparatus and circuits may be made Withoutdeparting from the spirit thereof. I desire, therefore, to be limitedonly by the scope of the appended claims.

I claim as my invention:

1. In a motor-control system, the combination with a motor armature, aplurality of reversing contactors therefor, and means operated by saidmotor for controlling said contactors, of a resistor, means coactingwith said reversing contaotors for connecting said resistor to saidarmature during dynamic braking, and means comprising a plurality ofadditional contactors for opening said armature circuit and completing adynamicbraking circuit through a portion of said resistor upon failureof said directional contactors to reverse said motor, said additionalcontactors being selectively operated in accordance with the directionof operation of said motor.

2. In a motor-control system, the combination with a motor having anarmature, a plurality of directional contactors therefor, and meanscontrolled by said motor for operating said contactors, of a resistor,means for connecting said resistor to said armature to secure dynamicbraking of said motor during normal 0 rat-ion and emergency means foreflectin g 'namic braking of said motor upon a fai ure of power, a rtionof said emergency means and a portlon of said connecting meansco-operating to effect dynamic braking of said motor upon the overtravelthereof.

3. In a motor-control system, the combination with a motor having anarmature, a plurality of directional contactors therefor, and meanscontrolled by said motor for operating said contactors, of a resistor,means coacting with said directional contactors for effecting dynamicbraking through the entire resistor, protective means operated by saidmotor during its overtravel for effecting dynamic braking through aportion of said resistor, and means for effecting dynamic braking ofsaid motor under low-voltage conditions by employing a still smallerportion of said resistor.

In testimony whereof, I have hereunto subscribed my name this 4th day ofAugust, 1920.

EDGAR M. BOUTON.

